Abstract: The Taoyuan gold deposit is situated within the Pingle Depression, located in the eastern segment of the Jiangnan Orogenic Belt, and represents a typical quartz vein-type gold deposit. Current understanding of the ore-forming material sources, the evolutionary history of ore-forming fluids, and the ore genesis of the Taoyuan gold deposit remains limited—particularly with respect to high-resolution in-situ microanalytical geochemical constraints. Through integrated field investigation and petrographic characterization, we identified multiple generations of scheelite, a critical accessory mineral whose compositional and isotopic signatures serve as robust tracers for constraining the origin and evolution of hydrothermal fluids. In-situ microscale geochemical and Sr isotope analyses of scheelite can provide novel insights into the genesis of gold deposits. This study employed a comprehensive suite of analytical techniques, including CL, LA-ICP-MS, and LA-MC-ICP-MS, to systematically investigate the major and trace element compositions and Sr isotopic characteristics of scheelite from different generations and mineralization stages within the Taoyuan gold deposit. Based on mineral assemblages and textural features, three distinct generations of scheelite have been identified: Sch-1, which exhibits oscillatory zoning and occurs in quartz-pyrite veins of the first mineralization stage; Sch-2a, characterized by oscillatory zoning and fragmentation within quartz-gold-polymetallic sulfide veins of the second mineralization stage; and Sch-2b, displaying dark CL and acting as a cementing phase for earlier-formed scheelite. All three generations of scheelite exhibit a rare earth element (REE) distribution pattern characterized by enrichment of middle REEs and relative depletion of light and heavy REEs. This pattern is highly consistent with that documented in scheelite from well-characterized quartz vein-type gold deposits worldwide. Integrated interpretation of the elevated Na concentrations in scheelite and the moderate salinity of coeval hydrothermal fluids, indicating that REE³⁺ and Na⁺ substitute for Ca²⁺ through an electrostatic compensation mechanism and selectively incorporate into the scheelite crystal lattice. Sch-1 and Sch-2a display pronounced positive Eu anomalies, whereas Sch-2b shows a weak negative Eu anomaly, suggesting a progressive increase in the oxygen fugacity of the ore-forming fluids from early to late mineralization stages. The observed increase in fluid oxygen fugacity is consistent with the influx of meteoric water during the late stage of mineralization. The ⁸⁷Sr/⁸⁶Sr ratios of scheelite across different generations are highly consistent (0.71236–0.71301), indistinguishable within analytical uncertainty from the age-corrected initial ⁸⁷Sr/⁸⁶Sr ratio of the Caledonian ore-hosting granodiorite. This isotopic congruence strongly indicates that the Sr in theo ore-forming fluid was predominantly dervied from the granodiorite host rock. Plagioclase dissolution during hydrothermal alteration releases Sr and abundant Ca, which combines with hydrothermal WO₄^2- to precipitate scheelite water-rock interactions between deep-source ore-forming fluids and host rocks played a crucial role in the formation of scheelite.